Motor pump or compressor package



Nov. 2, 1954 H. H. MCADAM 2,693,313

MOTOR PUMP OR COMPRESSOR PACKAGE Filed May 9, 1952 3 Sheets-Sheet l INVENTOR. HARRY H. Mc/JDAM WMh ATTORNEY NOV. 2, 1954 MCADAM 2,693,313

MOTOR PUMP OR COMPRESSOR PACKAGE Filed May 9, 1952 3 Sheets-Sheet 2 INVENTOR. HARRY Ma ADAM ATTORNEY Nov. 2, 1954 H. H. McADAM 2,693,313

MOTOR PUMP OR COMPRESSOR PACKAGE Filed May 9. 1952 3 Sheets-Sheet 3 INVENTOR. HARRY McADAM ATTORNEY United States Patent Ofitice 2,693,313 MOTOR PUMP OR COMPRESSOR PACKAGE Harry H. McAdam, San Carlos, Calif., assignor to Wetmore Hodges, doing business as Wetmore Hodges and Associates, Redwood City, Calif.

Application May 9, 1952, Serial No. 286,880 16 Claims. (Cl. 230-139) This invention relates to an improved motor-pump or compressor of the positive displacement type.

This invention solves many problems which have long confronted the pump and compressor industry, particularly in relation to such applications as compressors for domestic refrigerators, home freezers, and home air conditioners, water coolers, and other refrigerated devices.

One important problem has been to reduce the size, weight, and cost of compressors without interfering with their output performance. The present invention has solved this problem by placing the compressor completely inside an electric motor. It should be distinguished from attempted solutions by the prior art where the compressor was placed outside the motor, often on one end of it, and in which a common drive shaft connected the compressor to the motor. In the present invention there is no drive shaft or similar connection. As stated above, the compressor is directly inside the driving motor.

Another problem with prior art positive-displacement motor-compressors was that they required either an inlet valve, a discharge valve, or both. Being moving parts, the valves were subject to many types of trouble. The present invention has made it possible to do away with inlet and discharge valves and to replace them with simple ports. Nor are any other valves needed in the remainder of the system. The motor-pump or mo tor-compressor of this invention has operated successfully in a refrigeration system that had no valve of any kind anywhere in the system.

Two problems, related in their effects and solved by the present invention, were the effects in prior art compressors by torque reactions and by eccentric rotating masses. Torque reactions due to rapid momentary changes in load caused difficulties, for example, in pistontype compressors where large changes in load take place at the end of one compression stroke of the piston and the beginning of the next suction stroke. Eccentric masses caused problems in reciprocating and single vane rotary pumps. Wherever there was reciprocating motion and its resultant torque reaction and wherever eccentric masses rotated, there was considerable vibration,

so that counterbalances had to be applied to effect some i reduction of this disastrous vibration. Vibration dampeners or some other means for absorbing some of those shocks also had to be applied in order to reduce noise and wear. Heretofore all positive displacement compressors had either eccentric motion of reciprocating motion, or some other motion in which there were rapid changes in angular velocity or load and all of them resulted in either heavy torque reaction, rotational unbalance, oscillation or vibration, all highly objectionable.

The pump of the present invention has no eccentric rotating masses and is free from torque reaction, rapid load changes and oscillation. It has only two rotating parts, and they rotate about their respective centers at a constant rate, so that there is no change in angular velocity. .All the problems mentioned in the preceding paragraph, have therefore been solved.

Another problemin motor-pumps was that the lubrication systems of these units would not operate if the units were placed on their sides or upside down, or in angular positions. This inadaptability has been one cause for other design problems involving undesirable compromises in cabinet structure, piping systems and arrangement of related parts. The pump of the present 2,693,313 Patented Nov. 2, 1954 invention can operate in any attitude, novel type of lubrication system.

In addition to solving all the problems discussed above, the present invention also has brought many other unusual advantages. It is a remarkably simple apparatus, having only two moving parts and being held together by a single bolt. It can operate in any attitude with the same performance characteristics. It has none of the problems that occur where a common rotating drive shaft connects the motor to the pump, because there is no drive shaft of any kind. The pump is driven solely by electromagnetic force; there is no mechanical driving means. Having no drive shaft in any of its applications, no shaft seals are needed.

The present invention is a motor-pump or compressor in which all the pumping elements are mounted within the rotor of an electric motor. This rotor turns in a stator, and end plates in the stator provide stationary bearings that support the rotor for free rotation. This support and the engagement of the plates with the stator cavity bore, assure uniform clearance between the rotor and the statora factor that makes it possible to keep the air gap between the stator and the rotor unusually small. The end plates also locate and support the bearing around which the pinion gear of a gear pump may rotate. The end plates may also be used to provide support points for the resilient mounting of the entire apparatus. The fluid being pumped is taken in and is discharged through ports in the end closure plates, so that no intake and discharge valves are required.

Since the pump and compressor elements are completely contained inside the rotor and are driven by the rotor, the only two moving pump elements are: 1) an outer annular gear with interior teeth, which is secured to and driven by the rotor, and (2) an inner pinion gear driven by the outer gear. Both gears are perfectly symmetrical and are in natural dynamic balance. This structure solved the eccentric rotating mass problem, because the only two elements that rotate, do so in paths which are truly concentric to their individual centers: the pinion gear rotates about its true center, and the outer gear rotates abouts its own true center.

There is no rotating shaft, another feature that, so far as is known, is novel in this type of apparatus. Obviously, the absence of a rotating shaft eliminates the need for connecting rods, fluid seals, outboard bearings, overhung bearings, and so on. A novel type of positive lubrication system is employed in this pump. It operates without a sump and without the type of splash lubrication utilized in reciprocating pumps. The operation of this new lubrication system remains the same, whatever the attitude in which the unit is placed.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment thereof which will be described in detail in order to comply with the requirements of U. S. Revised Statutes, Section 4888. It should be understood that the details are illustrative and are given as examples and are not intended to narrowly limit the scope of the invention.

In the drawings:

Fig. 1 is a reduced view in perspective of a motor pump or compressor embodying the principles of this invention.

Fig. 2 is a view in section of a modified form of motor pump in which the pump is enclosed in an outer shell, the section being taken along the line 22 in Fig. 3.

Fig. 3 is a view in section taken along the line 33 of Fig. 2.

Fig. 4 is a view in section of the rotor of Fig. 3 and its contained parts, taken along the line 3-3 in Fig. 2 but looking in the opposite direction and with the pump gears rotated through a relatively small angle.

Fig. 5 is a view in perspective of the pump package.

Fig. 6 is a view in elevation of the cylindrical bearing for the inner pump element.

Fig. 7 is a view in elevation of a modified form of end plate having both an intake and discharge opening.

The electric motor pump 10 shown in Fig. 1 includes a hollow stator 11 within which a pump package 12 (see because it has a Fig. 5) may fit. The same pump package 12 isalso used in the motor pump 13 shown in Fig. 2 in which the stator 14 is enclosed in a shell 15. The reason there is no shell around the motor pump is that it is constructed according to the principles of my co-pending application, Serial No. 279,392, filed March 29, 1952 in which the stator 11 itself is impervious to fluid under pressure and forms a part of a fluid-tight pressure vessel. However, the present invention more particularly concerns the pump package 12, which has utility whether or not the motor-pump is enclosed in a shell.

The pump package 12 fits inside the stator bore 16 and includes end plates 17 and 18, a hollow rotor 2t), an outer gear or pump element 21 secured to the inside of the rotor 2%, and an inner gear or pump element 22. The inner gear 22 is inside the outer gear 21 and rotates around an axis C2 eccentric to the axis Ci of the rotor 2t and .the outer gear 21. The inner gear pump element 22 is supported by a stationary bearing member 23 which encircles the single stationary bolt Z' -t. When the rotor 2d rotates, the outer gear 21 drives the inner gear 22 and causes fluid to flow from the intake opening 25 to the discharge opening 26.

The stators 11 and 14 The stator 11 and the stator 1d may be made up of a plurality of thin iron laminations 3t) and wire windings 31. The stator 11 is constructed according to the principles of my invention described and claimed in Serial No. 279,392, filed March 29, 1952. its laminations 39 are secured together by a suitable plastic 32 (Fig. l) which may also fill the wire slots 33 (which are otherwise identical to those shown in Fig. 3) and encase the wires 31 where they stick out beyond the laminations 3t). However, this is not essential; the present invention will work in other types of hollow stators like the stator 14, where leakage of the fluid being pumped and loss of the pressure charge is prevented by a fluid-tight outer shell 15.

The end plates 17, 18

The end plates 17 and 18 perform many this device, including the support of the rotor vision for the intake and discharge openings 25, 26, and the support of the whole pump package 12 and/or the motor-pump it). The end plates 17., 13 are also recessed and drilled in certain places to provide grooves and passages that are part of the lubrication system for the motor pump.

In the forms of the invention shown in Figs. 1 and 2, the intake port 25 is in one end plate 17 while the discharge port 26 is in the other end plate 18. This is not necessary, as may be seen from Fig. 7, where a single end plate 35 has both an intake port 36 and a discharge port 37. Similarly, there may be more such ports.

In their general shape, the end plates 17, 1%, and 35 are substantially identical, consisting basically of a stepped disc 44 having a wider diameter outer portion 41, and a narrow diameter inner portion 42. The outer portion 41 may have a generally smooth outer rim 43 that nests in the stator bore 16 and serves there as a bearing surface.

The inner disc portion 42 preferably terminates in a fiat wall 44, which is preferably ground to insure that it has a perfectly plane surface. The periphery of the portion 42 is concentric with the rim 43 and forms a 'bearing surface for -rotatably supporting the motor rotor 2t). The proportioning, spacing, and concentricity of the two peripheries 43 and 45 insure perfectly accurate alignment and spacing of the pump package 12 in the stator 14, so that the rotor 20 is perfectly aligned and spaced, enabling the clearance area or air gap 46 between the rotor 27d and the stator it to be very small. This assures uniform rotor-to-stator clearance and uniform rotor-to-stator parallelism. The inner edge of the bear- 'ing 45 may be chamfered at 47 to facilitate assembly of the parts and a helical oil groove 45 maybe provided around the bearing 45.

The outer periphery of the disc portion 42 may be relieved at 59, and there may be an annular inset recess 51 to accommodate the portions of the rotor 2i which extend beyond the rotor bearings 45 and give adequate clearance between the end plates '17, 18 and the rotor 20.

The end plates 17, 18 may also be provided with an eccentrically located, preferably stepped, circular openfunctions in 2d, the proing 52 whose center C2 is radially offset with respect to the center C1 of the rim 43 and the bearing surface 47. The amount of offset depends on the amplitude of the gear teeth elements 21, 22 and all other related features of construction. The inner smaller diameter portion 53 of the opening engages the cylindrical body of the through-bolt 24, which extends beyond the shoulder 54 into the wider diameter portion 55 of the opening 52. Blind nuts 56 may be threaded on the outer ends 57 of the bolt 24 so that the nuts 56 abut the shoulders 54 and thereby urge the end plates 17, 13 inwardly against the cylindrical bearing member .23.

The end plate 17, which is provided with the intake opening 25 through which fluid is drawn into the pump, has, as part of the lubrication system, a bore 60 connecting the intake port with an annular groove 61 in the opening 52. The other end plate 18, which is provided with the discharge opening 26, also has an annular groove 62 in its opening 52, which is connected by a passageway 63 with an orifice 64 adjacent its outer periphery 43. The etfect of these lubrication passageways on the operation of the device will be discussed later.

The end plate 35 shown in Fig. 7 is like the end plates 17, 18 except that it has both an intake port 36 and a discharge port 37. The opposite end plate may have no ports it or it may also have an intake port or a discharge port or both. All of the intake and discharge ports 25', 26, 36, 37, may be threaded or otherwise adapted to receive the ends of suitable conduits thereon.

The motor rotor 20 The motor rotor 20 may be of the usual squirrel cage induction design having generally-annular projecting por tions 7% at each end. Annular bearings 71 may be provided on the inner surface of the central rotor bore 72. The bearings 71 ride on the bearings 45 of the end plates 17, 18 and are lubricated by oil which passes along the helical grooves -48.

The bearings 45 and 71 serve to locate the rotor 20 in relation to the stator 14 and thereby govern the air gap or clearance 46 between the parts. They also serve -to position the rotorZtl along its proper axis so that it rotates truly about the center C1.

The pump elements 21, 22 and the bearing 23 The outer pump element 21 may be press-fitted or otherwise secured to the rotor 29 in the bore 72 so that it becomes essentially integral with the rotor 20. In the drawings a hollow gear type of a pump element 21 is shown with a toothed inner surface 73.

The inner gear element 22 comprises a hollow cylindrical member having a toothed outer surface 7 5 driven by the toothed inner surface 73 of the outer element 21.

It will be obvious that the two pump elements 21, 22 rotate around different centers. The inner element 22 rotates around the center C2, and is made perfectly true and cylindrical so far as itself is concerned, its bore 75 and its teeth 74 being perfectly concentric. Similarly, the outer periphery 76 of the outer element 21 and its teeth 73 .are perfectly concentric, but the outer element 21 rotates around the center Ci because it is fastened to the rotor 20 and rotates therewith.

Preferably the inner and the outer gear elements 22 and 21 are of the so-called Rotoid type, that is, they preferably have an odd number of teeth, with the outer element 21 having two more teeth than the inner element 22. The teeth are preferably further constructed so that there is a sliding contact between the inner and outer elements 22, 21 which is not broken over a considerable are as the gears rotate. In the form of pump shown in the drawings, this arc will be about 240, with the open space 77 shown in Figs. 3 and 4 being about No claim is made herein to the use of Rotoid gears per se, but only when they are in combination with the other elements shown. The Rotoid elements them selves are described and claimed in Patent #2,547,392 issued April 3, 1951, to Myron P. Hill and Francis A. Hill, 2nd.

Between the inner gear element 22 and the bolt 24, is the cylindrical stationary bearing 23 which also acts as a stop and accurately spaces apart the end plates 17, 18, the nuts 56 being tightened on the bolt 24 until the flat surfaces 44 of both .end plates 17, 18 are in tight contact with the radial faces '78 of the bearings thereby placing the bearing under compression. The radial end spaced apart from the end plate provide a running clearance. For this purpose they are made almost, but not quite, as long as the bearing 23. A clearance of 0.0003 inch at each end has been used successfully.

The bearing 23 is preferably cylindrical and its inner surface 80 and outer surface 81 are concentric. The central portion 82 of the outer surface 81 is relieved, and a pair of helical grooves 83 are provided around the outer bearing surface including the surfaces 84 which engage the bore 75 of the inner gear element 22. These grooves 83 provide a path for the oil in the lubrication system which will be discussed later. Another part of the lubrication system is a radial bore 85 provided between the relieved portion 82 and an annular groove 86 provided in the interior surface 80 of the stationary bearing member 23.

The bolt 24 is provided with one or more axial grooves 87 on its outer surface which serve to connect the two annular grooves 61 and 62 in the end plates 17 and 18 and also communicate with the annular groove 86 in the bearing 23. Preferably the bolt 24 is provided with two such grooves 87 spaced diametrically apart.

As has been stated earlier, the bolt 24 and the bearing 23 are stationary, as are the end plates 17, 18 and the stator 14. The rotor 20 and the outer gear element 21, being fixed together, form one rotating element, and the inner gear element 22 is the only other rotating member. The position of the bolt 24 determines the center of rotation C2 of the inner gear element 22, and the positioning of the bolt 24 is determined by the construction of the end plates 17, 18. Thus the end plates 17, 18 must be made carefully in order to provide exactly the right eccentricity between the centers C1 and C2. When the end plates 17, 18 are properly constructed, the motor pump 13 is readily assembled. To prevent tampering by unskilled mechanics, the pump package 12 may be permanently sealed inside the motor stator 11 or 14, either by plastic or by spot welding, and it will continue to operate without the need for taking it apart.

faces of the gears are surfaces 44 enough to Assembly of the motor pump package 12 A preferred way of assembling the pump package 12 is to first thread one blind nut 56 to one end 57 of the through-bolt 24 and then to pass the through-bolt 24 through the opening 52 in one end plate 17. Then the hollow cylindrical bearing 23 may be placed around the through-bolt 24 and the inner gear 22 may be placed around the bearing 23. The rotor 20, with the outer gear 21 secured to it, may then be placed over the inner gear 22, the motor rotor bearings 71 being set to fully engage the bearing surface 45 on the end plate 17. The other end plate 18 may then be placed over the projecting bolt 24 and guided by the bolt 24 until its bearing 45 is in full engagement with the motor rotor bearing 71. The other blind nut 56 may then be threaded on its bolt end 57 and drawn up with suflicientfltension to achieve slight compression of the hollow cylindrical spacer bearing 23 between the end plates inner faces This completes the assembly of the piunp package 12, which is then ready to be inserted within the'stator bore 16.

Operation and lubrication When an electric current is applied to the windings of the stator 14, the rotor 20 will rotate on its bearings 71, 45. The outer pump element 21 being rigidly mounted to the rotor 20 will then drive the inner pump element 22, and fluid will be drawn in through the intake opening 25 and expelled through the discharge opening 26. The reason the fluid will be moved is fully explained in the Hill patent mentioned above and can be seen from Figs. 3 and 4 of the drawings. The present invention is an improvement over the Hill patents in that its Rotoid gears do not require any rotating shaft. In fact, other gears than Rotoid gears may be used, provided they make a seal when in mesh.

The lubrication system of pump 10 is composed of three circuits. The first circuit includes the other components of closed system, the pump 10 or 13 forming only a part of this closed system. In operation, some oil is discharged from the port 26 along with the pumped fluid. This oil circulates along with the pumped fluid throughout other parts of the system and finally reenters the pump through the intake opening 25.

The other two lubrication circuits are within the pump 10. Due to the positive displacement pumping action created when the gear elements rotate, a pressure difference exists between the pump intake and the pump discharge. This pressure ditference is a positive force that acts to drive oil and fluid from the higher pressure discharge portions of the pump toward the lower pressure intake portions. This force is utilized and controlled for forcing predetermined quantities of oil and fluid through the extremely small running clearances maintained between the end faces of the rotating gear elements 21 and 22 where they nearly abut the stationary plane surfaces 44 of the end plates 17 and 18. Since this running clearance is adjustable, the quantity of oil recirculated within the pump 10 is controllable.

Of the two recirculation lubrication circuits inside the pump 10, one is caused by the pressure that forces oil outwardly across both ends of the outer gear 21. After being forced through the running clearance at each end, the oil enters the helical grooves 48, in both end plates 17 and 18, and lubricates the bearing surfaces 45, 71. On leaving the helical groove 48 of the end plate 17, the oil is driven along the rotor 20 into the stator air gap 46, and flows toward the other end plate 18. Here it joins with oil leaving the groove 48 of the end plate 18, and enters the orifice 64. The oil is forced through the passage 63 in the end plate 18 and into the annular groove 62. From there it is driven along the axial grooves 87 in the bolt 24 to the annular groove 61 in the end plate 17. Then it flows through the passage in the end plate 17 into the intake port 25. From there the oil reenters the rotating gears 21, 22 to lubricate the meshing teeth and then is forced outwardly across the gear ends, to repeat the cycle.

The third of the three lubrication circuits includes the two streams of oil that are forced inwardly across both ends of the inner gear 22. These two streams of oil are forced under pressure through the running clearances between each end of the inner gear and the surfaces 44 of the end plates 17 and 18 until they reach the bearing 23. Each stream then enters the helical groove 83 at its end of the bearing 23 and lubricates its bearing surfaces 84 and 75. The two streams meet at the recessed area 82 of the bearing 23. The oil then goes through the passage 85 from the recess 82 into the annular groove 86 in the bore of the bearing 23. Here the oil of this third circuit joins with oil of the second circuit and flows along the axial grooves 87 to the groove 61 and through the passage 60 to the suction or intake port 25. Here the combined streams are joined with oil of the first lubrication circuit returning from the portions of the system outside the pump 10. The three joined oil streams then enter the rotating gears and the three cycles are repeated indefinitely.

The three circuits are all positive-pressure systems, so that recirculation is assured.

It will be evident that the lubrication system in no way depends upon the attitude of the pump so that the pump may be placed in any attitude without impairing any of its operations.

The simplicity of the pump, its freedom from'masses rotating off-center, its freedom from torque reaction, its positive lubrication system, its relatively small number of parts, the elimination of rotating shafts and of valves, make the pump one that can be made inexpensively and in a variety of sizes. Its performance is remarkably fine, and a pump a fraction of the size of prior art pumps may have a larger capacity. Finally, in view of the fact that there is no mechanical driving connection between the pump package and the stator, the pump package is interchangeable with other stators of the right size.

I claim:

1. An electric motor-pump,

including in combination a stator having a cavity;

a pair of end closure plates closing the opposite ends of. said cavity with their outer surfaces in contact with the cavity walls of said stator and having inwardly projecting circular bearing surfaces spaced radially from said stator; a hollow motor rotor rotatably mounted inside said cavity on said bearing surfaces; an outer symmetric pumping element inside said rotor and secured rigidly thereto; an inner symmetric pumping element mounted for rotation about a different center from the center of said outer element and driven by said outer element for moving and raising a fluid from a lower to a higher pressure; and intake and discharge means for-said fluid.

2. An electric motor-pump, including incombination astator having a cavity adapted to contain all the moving, parts of said motor-pump; a pair of end closure plates in said stator cavity and closing the opposite ends of said cavity, having inwardly projecting circular bearing surfaces spaced radially from said stator; a hollow motor rotor inside said stator cavity between said end plates, said rotor being rotatably mounted on said bearing surfaces; an outer pumping element inside said rotor and secured thereto; an inner pumping element rotatably mounted aboutits own center which is radially offset with respect to the center of said outer element; said inner element being driven by said outer element; for moving and raising a fluid from a lower to a higher pressure; and intake anddischarge means for said fluid.

3. An electric motor-pump, including in combination a pressure vessel adapted to contain at least the moving parts of said motor-pump; a stator having a cavity; a pairof end plates inside said cavity and closing the opposite ends of said cavity, said plates having cylindrical bearing surfaces spaced radially away from the walls of the stator; a hollow motor rotor inside said stator cavity between said end plates and rotatably mounted on said cylindrical bearing surfaces; an outer pumping element secured inside said rotor concentric therewith and driven thereby; a stationary bearing means extending between said end plates along an axis parallel to and radially offset from the axis of said cylindrical bearing surfaces; an inner pumping element rotatably mounted on said stationary bearing means and concentric therewith and in engagement with said outer pumping element for moving and raising a fluid from a lower to a higher pressure; and intake and discharge ports in the walls of said motor-pump.

4. An electric motor-pump, including in combination a pressure vessel adapted to contain the moving parts of said motor-pump; a stator having a cavity; a pair of end plates closing the opposite ends of said cavity, said plates having generally cylindrical bearing surfaces spaced radially away from the walls of the stator and having aligned off-center openings therethrough; a hollow motor rotor inside said stator cavity between said end plates and rotatably mounted on said bearing surfaces; an outer pumping element secured inside said rotor and driven thereby; a stationary cylindrical bolt-bearing means extending between said end plates and through their respective aligned off-center openings and secured to said end plates for holding them at a predetermined spacedapart interval; an inner pumping element rotatably mounted on said stationary bolt-bearing means and in engagement with said outer pumping element for moving and raising a fluid from a lower to a higher pres sure; and intake and discharge ports in the walls of said motor-pump.

l 5. A motor-pump, including in combination a pressure vessel; a hollow stator; a pair of end closure plates, at least one of which is ported so that said motor-pump has fluid intake and discharge means, said end plates fitting inside the stator bore and having cylindrical hearing surfaces spaced radially inwardly therefrom; a hollow motor rotor inside said stator and said vessel, rotatably mounted on said bearing surfaces; an outer symmetrical annular gear element secured inside said hollow rotor; a cylindrical bearing member held stationary between said end plates on a different center from said rotor; .and an inner symmetrical annular gear element mounted on said bearing member and drivenby said outer gear element for moving fluid between said intake and, discharge means.

6. A motor pump-package for insertion into the stator of an electric motor-pump, including in combination a pair of end plates each having a stepped rim with two coaxial annular bearing surfaces, at least one of said plates being ported, to provide intake and discharge means; a hollow motor rotor between said end plates rotatably mounted on the smaller diameter said bearing surfaces and with its vdiameter substantially as large as the diameter of said end plates except for an amount corresponding to a running clearance for said rotor, whereby said pump package may be inserted in said stator from one end thereof; and a pumping mechanism inside said rotor and driven thereby for moving a fluid therethrough.

3 .7. A pump package for insertion in the .bore of the stator of a motor-pump, including in combination a pair of end plates, at least one of which is ported so that said motor-pump has fluid intake and discharge means, said end plates each having two coaxial radially-instepped cylindrical bearing surfaces on their rims the larger diameter said bearing surface of said plates being adapted to bear against said stator bore, so that said pump package my be inserted into said stator bore as a unit; a hollow motor rotor rotatably mounted on the smaller diameter said bearing surfaces; an outer symmetrical annular gear element secured inside said hollow rotor; a cylindrical bearing member held sta-. tionary between said end plates on a difierent center from said rotor; and an inner symmetrical annular gear element mounted on said bearing member and driven by said outer gear element for moving fluid between said intake and discharge means;

8. A motor-purnp-package for insertion as a unit into a hollow motor stator including in combination a pair of end plates having a cylindrical bearing surface axially inset from its outer periphery, said outer, periphery being adapted to fit snugly in said stator, and having a fluid intake opening and a through-bolt opening through one plate and a fluid discharge opening and a through bolt opening through the other plate, said through-bolt openings being off. center with resact to said bearing surfaces; a hollow motor rotor rotatably supported on said bearing surfaces, and spaced between said end plates and smaller in diameter than the outer periphery of said end'plates only by an amount corresponding to a running clearance; an outer pumping element rigidly secured inside said rotor and driven by said rotor; a through-bolt passing between said through-bolt openings and holding said pump-package together; bearing means concentric with said through-bolt between said end plates; and an inner pumping element mounted con centrically on said bearing means and in engagement with said outer pumping element for moving fluid from said intake opening to said discharge opening.

9. A motor-pump-package for insertion as a unit into a hollow motor stator including in combination a pair of end plates each having a cylindrical bearing surface axially inset-from its outer periphery, said outer periphery being adapted to fit snugly inside said stator, said plates having a fluid intake opening and a fluid discharge opening; a hollow motor rotor rotatablysupported on said bearing surfaces and spaced between said end plates; an outer pumping element rigidly secured inside said rotor and driven by said rotor; means located off center with respect to said bearing surfaces for holding said end plates together at a spaced interval; and an inner pumping element mounted concentrically on said lastnamed means and in engagement with said outer pumping element for moving fluid from said intake opening to said discharge opening. Z

10. An electric motor-pump, including in combination a hollow, laminated and wire wound motor stator having a cavity; a hollow, laminated bar-and-end-ring, squirrel-cage motor rotor inside said stator,'said rotor also having a cavity; a pair of rotating, meshed, gear pumping elements one' inside the other, both inside said rotor; a stationary, hollow cylindrical bearing inside'said inner gear element; a pair of stationary, end closure plates having suitable fluid inlet and discharge openings and suitable through-bolt openings, said plates being sized to partially enter and close each end of said stator cavity, said plates being provided with integral bearings to partially enter, rotatably support and close each end of said rotor cavity, said end plate integral bearings being coaxial with the circular outer surfaces of said plates, so that the rotor to stator clearance is uniform; a stationary through-bolt, threaded at each end, said bolt passing through said hollow bearing and through both said end plates; and a pair of nuts engagingboth ends of said through-bolt and acting to draw in said end plates against said hollow bearing so that said bearing also serves as a spacer between said end plates.

11. A motor-pump, including in combination a pressure vessel containing at least the moving elements; a hollow stator having a circular bore therethrough; a pair of stationary end plates positioned at opposite ends of said bore, an outer circular rim of said end plates fitting snugly in said stator bore, said end plates each having a portion projecting inside said bore andspaced uniformly from the walls thereof to form circular bearing rims, an outer helical groove being provided in said rims, said plates having aligned off-center circular bolt openings therethrough, an inner annular oil groove being provided around each said off-center opening, one of said plates being provided with an intake port and said other plate being provided with a discharge port, and a passageway being provided in the plate having said discharge port between its said inner annular groove and a point adjacent the outer rim that supports said stator, and a bore being provided in the other said plate between its. said inner annular groove and said intake port; a stationary through-bolt running axially between said end plates through said oiT-center openings, said through-bolt having at least one axial oil groove on its outer surface extending the full length between said inner annular grooves; threaded means for securing each end of said bolt to its respective said end plate; a stationary hollow cylindrical bearing around said through-bolt and in contact therewith between said end plates and abutting said end plates to space them apart, said bearing having an annular oil groove on its interior surface at substantially its axial center, an annular recess on its exterior surface wider than its said groove and opposite thereto, a pair of helical oil grooves one on each of the non-recessed portions of said exterior surface leading from the outer edges of said bearing to said annular recess, and a bore connecting its said annular groove and its said recess for the passage of oil therethrough; an inner cylindrical symmetrical annular gear pump element having an odd number of teeth on its outer periphery rotatably mounted around said bearing and slightly shorter axially than said bearing, so that there is a small clearance between said elements radial faces and said end plates; a hollow motor rotor rotatably mounted on said bearing rims; an outer cylindrical gear pump element rigidly secured to said rotor inside said rotor and having interior teeth concentric to its outer periphery and therefore off-center with respect to said inner gear pump element, said outer element having two more teeth than said inner element and meshing therewith so that over a considerable are said elements are in sliding contact.

12. A motor-pump, including in combination a pressure vessel containing all the moving elements; a hollow stator having a circular bore therethrough; a pair of stationary end plates positioned at opposite ends of said bore, an outer circular rim of said end plates fitting snugly in said stator bore, said end plates each having a disc portion projecting axially inside said bore and spaced from the walls thereof to form circular bearing rims, said plates having aligned off-center circular bolt openings therethrough, at least one of said plates being provided with an intake port and at least one of said plates being provided with a discharge port; a stationary through-bolt running axially between said end plates through said off-center openings; threaded means for securing each end of said bolt to its respective said end plate; a stationary hollow cylindrical bearing around said through-bolt and in contact therewith between said end plates and abutting said end plates to space them apart; an inner cylindrical annular symmetrical gear pump element having an odd number of teeth on its outer periphery rotatably mounted around said bearing and slightly shorter axially than said hearing, so that there is a small clearance between said elements radial faces and said end plates; a hollow motor rotor rotatably mounted on said bearing rims; an outer cylindrical gear pump element rigidly secured to said rotor inside said rotor and having interior teeth concentric to its outer periphery and therefore off-center with respect to said inner gear pump element, said outer element having two more teeth than said inner element and meshing therewith so that over a considerable are said elements are in sliding contact.

13. A motor-pump, including in combination a hollow, laminated, wire-wound stator, a pair of stationary end plates held in said stator inside the stator bore, an outer circular rim of said end plates fitting snugly in said stator bore, said end plates each having an axially projecting portion inside said bore and spaced from the walls thereof to form circular bearing rims and having radially off-set axial openings therethrough, one of said plates being provided with an intake port and said other plate being provided with a discharge port, annular oil grooves being provided inside and around each said oifset opening and around and in each bearing rim and a bore for lubrication being provided in the plate having said discharge port between its said central opening groove and a point adjacent the outer rim that supports said stator, and a bore being provided in the other said plate between its said central opening groove and said intake port; a stationary securing through-bolt running axially between said end plates through said central opening, said through bolt having at least one axial oil groove on its outer surface extending the full length between said annular grooves in said central opening; a pair of nuts engaging each end of said bolt; a stationary hollow cylindrical bearing around said through-bolt and in contact therewith between said end plates and abutting said end plates to space them apart, said hearing having an annular oil groove on its interior surface at substantially its axial center, an annular recess on its exterior surface wider than its said groove and at substantially the axial center of said bearing, and a bore connecting its said groove and its said recess for the passage of oil therethrough; an inner cylindrical gear pump element having an odd number of teeth on its outer periphery and an opening concentric with its periphery rotatably mounted around said bearing and slightly shorter axially than said bearing so that it has a small clearance between its radial faces and said end plates; a hollow motor rotor rotatably mounted on said bearing rims; an outer cylindrical gear pump element rigidly secured to said rotor inside said rotor and having interior teeth concentric to its outer periphery and therefore ofiE-center with respect to said inner gear pump element, said outer element having two more teeth than said inner element and meshing therewith so that over a considerable are said elements are in sliding contact.

14. A closed pressure system for a fluid having lubricating qualities, including in combination a pressure vessel; an electric motor stator having a cavity; a pair of end plates at opposite ends of said cavity, said plates having inwardly projecting cylindrical bearing surfaces spaced radially away from the walls from said stator, said plates also having aligned off-center bolt openings, one of said end plates being provided with an intake port and the other said end plate being provided with a discharge port; a closed conduit connecting said discharge port to said intake port along a path outside said pressure vessel, for the conducting of fluid from said discharge port to said intake port; a hollow motor rotor inside said stator cavity between said end plates and rotatably mounted on said bearing surfaces; an outer pumping element secured inside said rotor and driven thereby; a stationary cylindrical bolt extending between said end plates and into said aligned off-center openings and secured to said end plates; a stationary hollow cylindrical bearing member around said bolt between said end plates and abutting the inner walls of said end plates so as to set them apart from each other; an inner pumping element rotatably mounted on said stationary bearing and in engagement with said outer pumping element for moving said fluid between said intake port and said discharge port along a path lying between said end plates; first lubrication passage means provided along the bearing surfaces where said rotor rotatably eugages said end plates; second lubrication passage means provided through the end plate having said discharge port from a point radially outward from said bearing surfaces and leading into the off-center opening of said end plate; third lubrication passage means provided from the outlet of said second lubrication passage means axially across said bolt between said bolt and said bearing to the off-center opening of the opposite said end plate; fourth lubrication passage means provided from said lastmentioned off-center opening to said intake opening; fifth lubrication passage means provided between said inner pumping element and said bearing; and sixth lubrication passage means provided to join said fifth lubrication passage means to said third lubrication passage means; whereby three forced lubrication circuits are set up in said closed pressure system; the first said lubrication circuit conducting oil from said discharge opening through said conduit to said intake opening and then between said pumping elements to said discharge opening, whence the cycle is repeated; the second circuit employing the pressure differential provided by the pumping elements to move the lubricant radially outwardly across both radial faces of said outer pumping element, then through both said first lubrication passage means, then into the area of clearance between said rotor and said stator, said lubricant being driven by said pressure toward the end plate having the discharge opening, and then consecutively through said second, third, and fourth lubrication passage means into said intake opening, whence the cycle of lubrication is repeated; the third said lubrication circuit utilizing the pressure differential between said intake and discharge ports to move the lubricant inwardly across both radial faces of said inner pumping element and then consecutively through said fifth, sixth, third, and fourth lubrication passage means into said intake port, whence said cycle of lubrication is repeated.

15. A closed pressure system for a fluid having lubrieating qualities, including in combination a pressure vessel; an electric motor stator having a cavity; a pair of end plates at opposite ends of said cavity, said plates having inwardly projecting bearing surfaces spaced radially away from the walls from said stator, one of said end plates being provided with an intake port and the other said end plate being provided with a discharge port; a closed conduit connecting said discharge port to said intake port along a path outside said pressure vessel, for the conducting of fluid from said discharge port to said intake port; a hollow motor rotor inside said stator cavity between said end plates and rotatably mounted on said bearing surfaces; an outer pumping element secured inside said rotor and driven thereby; a stationary bolt extending between and secured to said end plates, said bolt being located off-center with respect to said bearing surfaces; a stationary hollow cylindrical bearing member around said bolt between said end plates and abutting the inner walls of said end plates so as to set them apart from each other; an inner pumping element rotatably mounted on said stationary bearing and in engagement with said outer pumping element for moving said fluid between said intake port and said discharge port along a path lying between said end plates; first lubrication passage means provided along the bearing surfaces where said rotor rotatably engages said end plates; second lubrication passage means provided through the end plate having said discharge port from a point radially outward from said bearing surfaces and leading to said bolt; third lubrication passage means provided from the outlet of said second lubrication passage means axially across said bolt, between saidbolt and said bearing to the opposite said end plate; fourth lubrication passage means provided through said 'lastnamed end plate to its said intake opening; fifth lubrication passage means provided between said inner pumping element and said bearing; and sixth lubrication passage means provided tojoin said fifth lubrication passage means to said third lubrication passage means; whereby three forced lubrication circuits are set up in said closed pressure system; the first said lubrication circuit conducting oil from said discharge opening through said conduit to said intake opening and then. between said pumping elements to said discharge opening, whence the cycle is repeated; the second circuit employing the pressure differential provided bythe pumping elements to move the lubricant radiall'youtwardly across. both radial faces of said outer pumping element, then consecutively through said first, second, third, and fourth lubrication passage means; whence the cycle of lubrication. is repeated; the third said lubrication. circuit utilizing the pressure differential between said intakeand discharge ports to. move the lubricant inwardly across. both radial faces of said inner pumping element and then consecutively through said fifth, sixth, third, and fourth lubrication passage means into said intake. port whence said cycle of lubrication is repeated;

16. A shaftless electric motor-pump including in. combination a stator having a. cavity, and a unitary pump package adapted for insertion, as a pre-assembled unit in said stator cavity, said pumpv package; comprising: a. pair of generally radial end; plates adapted-,when saidpackage is inserted, to close the. opposite endsof: the stator cavity, their peripheral, walls fitting snugly; against the axial walls of the stator cavity; said. plates: each having; annular hearing surfaces concentric with. their outer peripheries extending axiallyinto said; stator cavity, at least one of said plates being ported so that said motor-pumpv has intake and discharge means; a, hollow motor-rotor between said endplates and. rotatable, on; said bearing surfaces, which extend part way intothe hollow through said: rotor; an outer symmetric pumping element inside saidrotor and secured rigidly directly thereto; a; stationary bearing cyle inder extending axially between said end plates with its axis radially offset from. the axes, of said. end plates; and an inner symmetric pumping element rotatably mounted on said stationarybearing cylinder so as to be; driven by said outer pumping element: so that they move fluid between saidintake and discharge means.

References Cited in the file of. this patent UNITED STATES PATENTS Number Name Datel',631,592 June 7, 1927 1,780,338 Canton; Nov. 4, 1930 1,780,339. Canton Nov. 4, 1 930 1,849,222 Canton Mar. 1 5, 193.2 2,246,275. Davidson, J3une 17, 194.1 2,415,011 Hubacker Ian, 28, 1947 2,519,580 Kittleson Aug; 22', 1950 2,547,392 Hill. etal'. Apr.. 3,, 195.1 

